METHODS AND APPARATUS FOR A MICROWAVE BATCH CURING PROCESS
FIELD
[0001] Embodiments of the present disclosure generally relate to microwave batch curing processes.
BACKGROUND
[0002] Curing refers to toughening or hardening of polymer material by cross- linking of polymer chains. Conventional curing is done by furnace curing which takes place at a higher temperature as compared to microwave curing. Conventional curing typically takes more than 6 hours at greater than 220 degrees Celsius. However, the inventors have observed that a microwave curing process can be done under 1 hour and at less than 200 degrees Celsius. While furnace curing is slower as compared to microwave curing, due to the sheer volume of semiconductor wafers a conventional curing chamber can handle, the throughput of a conventional curing chamber outnumbers the faster microwave curing process. Therefore the inventors believe that there is a need to have a microwave compatible batch chamber that can match throughput of conventional curing without compromising curing uniformity within the batch.
[0003] Accordingly, the inventors have developed improved methods and apparatus for a microwave batch curing process.
SUMMARY
[0004] Methods and apparatus for a microwave batch curing process are provided herein. In some embodiments, an process chamber for a microwave batch curing process includes: an annular body having an outer surface and an inner surface defining a central opening of the annular body, wherein the inner surface comprises a plurality of angled surfaces defining a first volume; a first lip extending radially outward from the outer surface of the annular body proximate a first end of the annular body; a second lip extending radially outward from the outer surface of the annular body proximate a second end of the annular body; an exhaust disposed between the first lip and the second lip and fluidly coupled to the first volume, wherein the exhaust comprises a plurality of first openings; a plurality of second openings fluidly coupled to the first volume, wherein the plurality of second openings are configured to expose the first volume to microwave energy; and one or more ports fluidly coupled to the first volume.
[0005] In some embodiments, a process chamber for a microwave batch curing process includes: a plurality of annular bodies in a stacked configuration, wherein each annular body includes: an outer surface and an inner surface defining a central opening of the annular body, wherein the inner surface comprises a plurality of angled surfaces, and wherein the pluralities of angled surfaces of the plurality of annular bodies together define a first volume; a first lip extending radially outward from the outer surface of the annular body proximate a first end of the annular body; a second lip extending radially outward from the outer surface of the annular body proximate a second end of the annular body; an exhaust disposed between the first lip and the second lip and fluidly coupled to the first volume, wherein the exhaust comprises a plurality of first openings; a plurality of second openings fluidly coupled to the first volume, wherein the plurality of second openings are configured to expose the first volume to microwave energy; and one or more ports fluidly coupled to the first volume. The process chamber further includes a lid disposed atop a topmost annular body to seal an upper portion of the first volume; and a substrate transfer apparatus disposed beneath and coupled to a bottommost annular body for transferring a plurality of substrates into and out of the first volume.
[0006] In some embodiments, a method of performing a microwave batch curing process includes: providing a plurality of substrates to a process chamber comprising: an annular body having an outer surface and an inner surface defining a central opening of the annular body, wherein the inner surface comprises a plurality of angled surfaces defining a first volume; a first lip extending radially outward from the outer surface of the annular body proximate a first end of the annular body; a second lip extending radially outward from the outer surface of the annular body proximate a second end of the annular body; an exhaust disposed between the first lip and the second lip and fluidly coupled to the first volume, wherein the exhaust comprises a plurality of first openings; a plurality of second openings fluidly coupled to the first volume, wherein the plurality of second openings are configured to expose the first volume to microwave energy; and one or more ports fluidly coupled to the first volume; forming a vacuum within the apparatus; and exposing the plurality of substrates within the apparatus to microwaves.
[0007] Other and further embodiments of the present disclosure are described below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Embodiments of the present disclosure, briefly summarized above and discussed in greater detail below, can be understood by reference to the illustrative embodiments of the disclosure depicted in the appended drawings. However, the appended drawings illustrate only typical embodiments of the disclosure and are therefore not to be considered limiting of scope, for the disclosure may admit to other equally effective embodiments.
[0009] Figure 1 depicts a schematic view of a process chamber for a microwave batch curing process in accordance with some embodiments of the present disclosure.
[0010] Figure 2 depicts a schematic view of a process chamber for a microwave batch curing process in accordance with some embodiments of the present disclosure.
[0011] Figure 3 depicts a schematic view of two process chambers for a microwave batch curing process in accordance with some embodiments of the present disclosure.
[0012] Figure 4 depicts a schematic view of a pressure sensor coupled to a process chamber for a microwave batch curing process in accordance with some embodiments of the present disclosure.
[0013] Figure 5 depicts a schematic view of a temperature sensor coupled to a process chamber for a microwave batch curing process in accordance with some embodiments of the present disclosure.
[0014] Figures 6A-6B respectively depict schematic side views of multiple process chambers for a microwave batch curing process in accordance with some embodiments of the present disclosure. [0015] Figure 7 depicts a flowchart of a method for performing a microwave batch curing process in accordance with some embodiments of the present disclosure.
[0016] Figure 8 depicts a schematic view of a process chamber for a microwave batch curing process in accordance with some embodiments of the present disclosure.
[0017] Figure 9 depicts a cross-sectional view of a process chamber for a microwave batch curing process in accordance with some embodiments of the present disclosure.
[0018] Figure 10 depicts a schematic view of a multiple process chamber apparatus for a microwave batch curing process in accordance with some embodiments of the present disclosure.
[0019] Figure 1 1 depicts a cross-sectional view of a process chamber for a microwave batch curing process in accordance with some embodiments of the present disclosure.
[0020] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. The figures are not drawn to scale and may be simplified for clarity. Elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation.
DETAILED DESCRIPTION
[0021] Methods and apparatus for improved microwave batch curing processing are provided herein. The present disclosure provides an improved microwave batch curing process apparatus that may be utilized with a range of microwave frequencies for semiconductor manufacturing processes. Embodiments of the apparatus of the present disclosure may advantageously provide one or more of the following: spreading microwaves uniformly throughout the apparatus; minimizing or eliminating leakage of microwaves from the apparatus, attaining proper vacuum conditions, or minimizing or eliminate particle generation. In addition, embodiments of the apparatus of the present disclosure may be utilized in a configuration that advantageously provides flexibility in processing a variable number of substrates. [0022] Figure 1 and Figure 2 depict schematic views of a process chamber 132 for a microwave batch curing process in accordance with some embodiments of the present disclosure. The process chamber 132 comprises an annular body 100. The annular body has a thickness sufficient for use as a microwave chamber as well as for assembly and use in batch processing substrates as disclosed herein. In some embodiments, the annular body 100 has a thickness of about 1 inch. In some embodiments, the annular body 100 has outer dimensions of about 22 inches by 22 inches by 8 inches, although other dimensions may be used, for example, when processing substrates having smaller or larger dimensions. In some embodiments, the annular body 100 is composed of aluminum. For example, in some embodiments, the annular body 100 is composed of an alimex material.
[0023] In some embodiments, the process chamber includes one or more cooling channels to circulate a cooling fluid (e.g., a coolant) to control the temperature of the process chamber during use. For example, as depicted in Figure 9, in some embodiments, the process chamber 132 comprises a plurality of channels 900 within the annular body 100 to circulate a cooling fluid. The plurality of channels 900 include an inlet 902 and an outlet 904 to facilitate circulating the cooling fluid (provided from a cooling fluid source) to prevent the outer surface of the annular body 100 from exceeding a predetermined temperature. In some embodiments, the predetermined temperature is about 65 degrees Celsius.
[0024] The annular body 100 comprises an outer surface 102 and an inner surface 104. The inner surface 104 defines a central opening 106 of the annular body 100. The inner surface 104 comprises a plurality of angled surfaces 1 10 defining a first volume 1 12. Each of the angled surfaces may be planar and parallel to a central axis of the annular body 100. Each of the angled surfaces may be arranged to have an equal included angle between each pair of adjacent angled surfaces One or more substrates, for example semiconductor wafers or other substrates having materials to be microwave cured may be disposed within the first volume 1 12 during curing operations. In some embodiments, the inner surface 104 has five (5) or more angled surfaces. In some embodiments, as depicted in Figures 1 -3, the inner surface 104 has eight (8) angled surfaces. In some embodiments, for an inner surface 104 having 8 angled surfaces, the angle 105 between each angled surface 1 10 (i.e. between an angled surface 1 10 and an adjacent angled surface 1 10) is about 135 degrees. In some embodiments, for example Figure 8, the inner surface 104 has twelve (12) angled surfaces. In some embodiments, for an inner surface 104 having 12 angled surfaces, the angle 105 between each angled surface 1 10 (i.e. between an angled surface 1 10 and an adjacent angled surface) is about 150 degrees. The inventors have observed that an inner surface 104 having a plurality of angled surfaces advantageously provides more uniform reflection and more uniform distribution of microwave energy, unlike a completely circular inner surface which will concentrate microwave energy at the center of the first volume 1 12. For example, the inventors have observed that a process chamber 132 having an inner surface 104 having, for example, 8 angled surfaces or 12 angled surfaces advantageously distributes microwaves uniformly throughout the first volume 1 12 to provide uniform curing of substrates within the first volume 1 12. Other numbers of angled surfaces may also be used, including more than 12 angled surfaces, although increasing numbers of angled surfaces may begin to approximate a circular inner surface.
[0025] The annular body 100 further comprises a first lip 1 14 (or first flange) and a second lip 1 18 (or second flange). The first lip 1 14 extends radially outward from the outer surface 102 of the annular body 100 proximate a first end 1 16 of the annular body 100. The second lip 1 18 extends radially outward from the outer surface 102 of the annular body 100 proximate a second end 120 of the annular body 100.
[0026] In some embodiments, the first lip 1 14 comprises a first groove 128 disposed within a first surface 130 of the first lip 1 14. In some embodiments, the first groove 128 is annular or substantially annular. In some embodiments, the first groove 128 has an opening with a width of about 0.27 inches. The first groove 128 is configured to retain a seal, such as an O-ring or similar gasket material, to form a seal when multiple process chambers 132 are in a stacked configuration, as described below with respect to Figure 3. In some embodiments, as depicted in Figure 2, the second lip 1 18 comprises a second groove 210 disposed within a first surface 212 of the second lip 1 18. In some embodiments, the second groove 210 is annular or substantially annular. In some embodiments, the second groove 210 has an opening with a width of about 0.094 inches. In some embodiments, the second groove 210 holds a conductive gasket to more robustly ground the process chambers 132 when multiple process chambers 132 are in a stacked configuration, as described below with respect to Figure 3.
[0027] The annular body 100 further comprises an exhaust 122 disposed between the first lip 1 14 and the second lip 1 18. The exhaust 122 is fluidly coupled to the first volume 1 12. The exhaust 122 may generally have any shape and size to facilitate sufficient flow to maintain process parameters in the chamber, such as a desired pressure. In some embodiments, as depicted in Figures 1 -3, the exhaust 122 may be rectangular, for example, having dimensions of about 1 1 inches by about 4 inches. In some embodiments, as depicted in Figure 8, the exhaust 122 may be circular in shape. The exhaust 122 comprises a plurality of first openings 124 fluidly coupled to the first volume 1 12. In some embodiments, each of the plurality of first openings 124 comprises a diameter of less than about 10 mm.
[0028] The process chamber 132 is suitable for receiving variable frequency microwave energy having a frequency of less than about 6.9 GHz, for example about 4.5 GHz to about 6.9 GHz. In some embodiments, the process chamber 132 utilizes 4096 frequencies swept across the chamber in about 0.1 seconds over a frequency range of about 5.8 to about 6.9 GHz. The inventors have observed that any openings in the process chamber 132 that are greater than about one-half the wavelength of the microwave will undesirably leak out from openings in the process chamber 132. Thus, a diameter of less than about 10 mm for the plurality of first openings 124 advantageously exhausts gases from within the first volume 1 12 while preventing leakage of microwaves from the first volume 1 12. In some embodiments, the number of first openings 124 is chosen to match the conductance of the turbo pumps (not shown) coupled to the process chamber 132 for suction.
[0029] The annular body 100 further comprises a plurality of second openings 126 fluidly coupled to the first volume 1 12. The plurality of second openings 126 facilitate delivery of the microwave energy to the first volume 1 12. For example, each second opening 126 may be rectangular. In some embodiments, each second opening 126 may include angled sidewalls that enlarge the opening on a side of the opening facing the first volume 1 12. In some embodiments, the second openings 126 are disposed along the inner surface 104. In some embodiments, the second openings 126 are staggered, or spaced apart, along the inner surface 104. For example, in some embodiments as depicted in Figure 1 and 2, the annular body 100 comprises two second openings 126, wherein the two second openings 126 are disposed along the inner surface 104 opposite each other. For example, in some embodiments as depicted in Figure 8, the annular body 100 comprises four second openings 126, wherein two of the four second openings 126 are disposed along the inner surface 104 opposite to each other and the other two second openings 126 are disposed along the inner surface 104 opposite to each other but not opposite to the first two second openings 126. For example, each of the second openings 126 may be equidistantly spaced about the annular body 100 (e.g., about 90 degrees apart in the embodiment depicted in Figure 8). In some embodiments, for example as depicted in Figures 1 and 2, each second opening 126 is a singular opening at the inner surface 104. In some embodiments, for example as depicted in Figure 8, each second opening 126 comprises multiple openings at the inner surface 104.
[0030] As depicted in Figure 2, the annular body 100 comprises one or more ports 200 from the outer surface 102 through the inner surface 104 and fluidly coupled to the first volume 1 12. In some embodiments, the one or more ports 200 comprise a first port 202 and a second port 204 having a diameter of less than about 10 mm. As described above, having a diameter of less than about 10 mm prevents leakage of microwaves from the first volume 1 12 through the one or more ports 200.
[0031] In some embodiments, as depicted in Figure 2, a temperature sensor 206 is disposed within the first port 202 to measure a temperature within the first volume 1 12. Figure 5 depicts a schematic cross-sectional view of a temperature sensor 206 coupled to the annular body 100 via the first port 202.
[0032] In some embodiments, as depicted in Figure 2, a pressure sensor 208 is coupled to the annular body 100 to measure the pressure within the first volume 1 12 via the second port 204. Figure 4 depicts a schematic cross-sectional view of a pressure sensor 208 coupled to an isolation valve 500 via a clamp 502. The isolation valve 500 is coupled to the annular body 100 at the second port 204. [0033] In some embodiments, as depicted in Figure 3, a plurality of process chambers 132 may be coupled in a stacked configuration. For example, as depicted in Figure 3, two process chambers 132 may be coupled in a stacked configuration. In some embodiments, as depicted in Figure 3 the second lip 1 18 of the top body 300 is coupled to the first lip 1 14 of the bottom body 302. In some embodiments, the top body 300 is coupled to the bottom body 302 via suitable fasteners such as bolts or screws. In the stacked configuration as depicted in Figure 3, the first volume 1 12 of the top body 300 is fluidly coupled to the first volume 1 12 of the bottom body 302. The first volume 1 12 of each body may hold, for example up to about 10 semiconductor wafers or other suitable substrates. The inventors have observed that the stackable configuration of the process chambers, as depicted in Figure 3, advantageously provides the capability to handle batch wafers and provides the flexibility of choosing the number of wafers to be processed by increasing or decreasing the process chamber volume accordingly. The flexibility in process chamber volume allows for optimization of substrate cycle time depending upon substrate load. The top most process chamber in a stacked configuration, for example top body 300 in Figure 3, includes a lid 304 to seal the first volume 1 12. The top most process chamber has a lid 304 disposed atop the process chamber to seal the first volume 1 12.
[0034] In some embodiments, one or more process chambers, as described above, may be stacked atop a substrate transfer apparatus 610 for transferring a plurality of substrates into and out of the process chambers. For example, Figures 6A and 6B depict a substrate transfer apparatus 610 having a lower chamber 600. As depicted in Figure 6A, the lower chamber 600 holds a plurality of substrates 602. In some embodiments, the plurality of substrates 602 are aligned parallel to each other in a stacked configuration. One or more process chambers 608 as described above are disposed atop the lower chamber 600.
[0035] The top most process chamber of the one or more process chambers 608 has a lid 304 disposed atop the process chamber to seal the first volume 1 12 in the manner discussed above with respect to Figure 3. While Figures 6A and 6B depict three process chambers 608 aligned in a stack above the lower chamber 600, as described above, more or less than three process chambers 608 may be utilized dependent upon the number of substrates to be processed.
[0036] As depicted in Figure 6B, the plurality of substrates 602 can be positioned within the first volume 1 12 of the one or more process chambers 608. A lift mechanism 604 is provided to lift the plurality of substrates 602 from the lower chamber 600 into the first volume 1 12 of the one or more process chambers 608. The lift mechanism 604 may be any suitable lift mechanism, such as an actuator, motor, or the like. In some embodiments, the lift mechanism is coupled to a substrate support 612 that may be disposed in the lower chamber 600 or moved into the inner volume of the one or more process chambers 608. A plurality of moveable supports 614 are movably coupled to sidewalls 616 of the substrate transfer apparatus 610. A plurality of arms 618 have a first end coupled to the substrate support 612 and a second end coupled to the moveable supports 614. The moveable supports 614 move linearly along the sidewalls 616 of the substrate transfer apparatus 610 to raise or lower the substrate support 612 via the plurality of arms 618. Once the plurality of substrates 602 are raised into the first volume 1 12, a lower plate 606 coupled to the substrate support 612 seals a volume of the lower chamber 600 from the first volume 1 12 to prevent escape of microwaves and maintain a predetermined pressure in the first volume 1 12. The lower plate 606 butts up against, or mates with, an adapter 613 such that there is no gap, or a minimal gap, between the lower plate 606 and the adapter 613, thus sealing the first volume 1 12. The adapter 613 is coupled to an inner surface of the lower chamber 600. Figure 1 1 depicts a schematic view of the lower plate 606 and the adapter 613 forming a seal to prevent escape of microwaves and maintain a predetermined pressure in the first volume 1 12. As depicted in Figure 1 1 , the lower plate 606 comprises a first portion 1 102 that forms seal with a first portion 1 104 of the adapter. The lower plate 606 further comprises an edge portion 1 106 having an annular opening 1 1 14, for example a groove or a trench, having a predetermined width. The annular opening 1 1 14 comprises one or more protrusions 1 108 extending away from a surface 1 1 10 of the annular opening 1 1 14 toward a surface 1 1 12 of the adapter. In some embodiments, the multiple protrusions 1 108 may be separated by a gap (not shown) of predetermined size. In some embodiments, the protrusions 1 108 may extend perpendicular to the surface 1 1 10 of the annular opening 1 1 14. In some embodiments, the protrusions 1 108 may extend at a predetermined angle to the surface 1 1 10 of the annular opening 1 1 14.
[0037] Figure 10 depicts a schematic view of a multiple process chamber apparatus 1000 for a microwave batch curing process in accordance with some embodiments of the present disclosure. Figure 10 depicts one or more process chambers 1004 as described above, stacked atop a substrate transfer apparatus 610 for transferring a plurality of substrates into and out of the process chambers. The substrate transfer apparatus 610 comprises a lower chamber 600 to hold a plurality of substrates 602. As explained above with respect to Figure 6B, the plurality of substrates 602 can be transferred from the lower chamber 600 to the first volume 1 12 of the one or more process chambers 1004. The top most process chamber 1004 of the one or more process chambers 1004 has a lid 304 disposed atop the process chamber 1004 to seal the first volume 1 12 in the manner discussed above with respect to Figure 3. While Figure 10 depicts three process chambers 1004 aligned in a stack above the lower chamber 600, as described above, more or less than three process chambers 1004 may be utilized dependent upon the number of substrates to be processed. Figure 10 further depicts an exhaust system 1002 coupled to the exhaust 122 of each process chamber 1004.
[0038] Figure 7 depicts a flowchart of a method 700 for performing a microwave batch curing process in accordance with some embodiments of the present disclosure. At 702, and as depicted in Figures 6A and 6B, a plurality of substrates 602 is provided to the first volume 1 12 of one or more process chambers 608 aligned in a stack and having the features described above. As depicted in Figures 6A-6B, the plurality of substrates 602 may be provided to the first volume 1 12 of the process chambers 608 from a lower chamber 600 via a lift mechanism 604. Next, at 704, a vacuum is formed within the first volume 1 12 by exhausting gases through the exhaust 122. Next, at 706, the plurality of substrates 602 within the first volume 1 12 is exposed to microwave energy for a suitable amount of time to undergo a microwave curing process. As described above, the angular surfaces of the inner surface 104 advantageously provides uniform reflection and uniform distribution of microwave energy to cure the plurality of substrates 602. Following the curing process, the plurality of substrates 602 are lowered from the first volume 1 12 into the lower chamber 600 and removed for further semiconductor manufacturing processes.
[0039] While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof.